1. Field of the Invention
The present invention relates to an production line of a car component, and especially relates to a production line for producing car doors by welding.
2. Background Art
Conventionally, when producing a car, especially when assembling a white body by welding prior to painting, it is necessary to input a pair of left and right car body components constituting the white body at the same time.
Compared with large components such as a body side assembly or a floor assembly, since car components such as a front door and a rear door are sub-assembled by a number of processes, and since the right hand and the left hand doors are shaped into different forms even though they are mirror images, those doors have been normally produced by separate lines.
Practically, the front doors are produced as follows. The front door comprises a door panel as an inner member, a door skin as an outer member, a door sash member, and a hinge mount reinforcing member and thus, the production of the door requires the assembly of numerous elements in a number of assembly processes. At the same, since the door forms part of the outer body of the car which attracts much attention, and since it is necessary to form a clear parting line between the body side assembly and the car door, the car door must be formed very accurately. In addition, the production of the car door necessitates a numerous welding processes so that the door skin is joined to the inner door panel by hemming processing and the periphery of the hemming processed door assembly is welded for integrating both door panel and the door skin.
However, when the front doors and the rear doors are produced by the respective separate lines, a problem arises in that the working efficiency, in other words, the productivity of car doors, is low, and the cost of equipment becomes high. That is, separate production lines for right and left doors which are different in shape but require the same production processes using the same production machines, lower the production efficiency and productivity and raises the cost of equipment.
Furthermore, another problem arises, if the left and right doors are produced by two different lines in synchronism with each other for producing both doors at the same accuracy, it becomes necessary to synchronize both production lines as much as possible, which leads to complicated operation controls.
The other problem in producing left and right doors in separate lines is that, although similar jigs and molds are used in those lines, it is difficult to control and to preserve high dimensional accuracy of jigs and molds for separate lines.
It is therefore an objective of the present invention to provide a production line which is capable of producing a pair of car components, with high operating efficiency and high productivity, and is also capable of producing high quality products while managing the jigs and molds at high accuracy.
According to the first aspect of the present invention, a production line of a car component for manufacturing a pair of left and right car components of a car body comprises: a work supplying portion for alternately supplying two types of works; a transfer and processing portion for processing one of the works while transferring another; wherein said work supplying portion and said transfer and processing portion are arranged to form one production line by addition of a finished car component delivery portion.
The production line according to the first aspect makes it possible to assemble a pair of left and right works simultaneously by one line through transfer, processing, and delivery portions to the left and right door assemblies for delivering to the white body assembly line.
According to the second aspect of the present invention, the work supplying portion comprises a turn table (for example, the turn table 1 in the embodiment), which can turn to the work input portion, and first jigs for mounting the left and right works, and second jigs (for example, the setting jigs 2 in the embodiment) for positioning and attaching welding parts to be welded to the left and right doors, wherein said turntable and first and second jigs constitute a work tack welding process together with welding robots (for example, the welding robot 4 in the embodiment) arranged around said turntable.
The production line according to the second aspect makes it possible to assemble the left and right door assemblies very efficiently, since the left and right works are mounted alternately on a first jig by turning the turning tables, and when one of the left or right work is delivered after being welded by the welding robot, another work is supplied for welding by the turning of the turntable.
According to the third aspect, said transfer and processing portion comprises an incremental welding process for incremental welding of said first work and said welding parts at the tack welded state, a marriage process for combining said first work with a second work to be integrated with said first work, and a hemming process for integrating said first and second works by bending either one periphery of said first and second works.
The production line according to the third aspect makes it possible to process one of the left and right works, while transferring another one of the left and right works in the incremental welding process, in the marriage process and in the hemming process, respectively. Since the respective transfer periods of these processes are loss periods in the production line, elimination of the loss time effectively improves the productivity.
According to the fourth aspect, the car component comprises a pair of front doors or a pair of rear doors.
Formation of the production line according to the fourth aspect makes it possible to reduce the assembly period of both left and right front door assemblies or both left and right rear door assemblies. Furthermore, the above production line makes it possible to ensure the dimensional accuracy of these door assemblies, which is desirable because these door assemblies turn out to include the outer panel which determine the quality of the car appearance.
According to the fifth aspect, said works comprise the inner member or the outer member of the front door and rear door, said welding parts comprise a door sash member and a door hinge mount reinforcing member, and said attachment members comprise the inner member and outer member of the front door or the rear door.
The production line according to the fifth aspect makes it possible to assemble the left and right door assemblies in one line by combining the inner panel member or an outer panel member of the front or rear door with various welded parts comprising a door sash member or a door hinge mount reinforcing member.